No one knew it at the time, but the key moment in the Supreme Court Obamacare case came on March 26, the first day of oral arguments, when few people were paying close attention.

Before getting to the heart of the case, the justices first wanted to deal with what seemed to be a side issue: Was the penalty imposed by the individual mandate in Obamacare a tax? If it was, the case would run afoul of a 19th century-law known as the Anti-Injunction Act, which said a tax cannot be challenged in court until someone has actually been forced to pay it. Since the Obamacare mandate wouldn’t go into effect until 2014, that would mean there could be no court case until then.

No one had challenged Obamacare on that basis; the challengers wanted the case to go forward now. The White House, having argued strenuously during the Obamacare debate that the penalty wasn’t a tax, wanted to go ahead as well. So the court, on its own, tapped a Washington attorney to make the argument that the penalty was a tax and therefore the case should not go ahead.